As is known endoscopic technique was developed in the medical field with the aim to improve the evaluation of the human hollow cavities. Gastrointestinal tract was one of the first places that were captured by endoscopic procedures. Prior art in this field includes the design of endoscope, a well-known optical system that was disclosed and claimed in U.S. Pat. No. 3,449,037 issued to C. J. Koester on June 1969. Currently used fiberoptic endoscopes are comprised of many lenses mounted in a flexible tube to relay an image from inside a body cavity for viewing by a physicians for diagnosis or manipulation inside those cavitary spaces. Colonoscope is one of these instruments that can be used to investigate the large bowel. Colonoscope is pushed inside the colon through anal canal. As long as this instrument moves straight, the friction force is trivial and nearly all the forward pushing force transmits through the shaft to the tip of the colonoscope and this force moves the tip of the colonoscope to ward the front (FIG. 1, drawing sheet 1). However the human colon is not a straight conduit and passing bends or flexures of the colon, will stretch the colon over the passing fiberscope and this will result in large friction and shearing forces that would resist onward movement of the fiberscope. At this stage the pushing force over the shaft of colonoscope, has to overcome the friction and shearing forces to move the tip ahead (FIGS. 2,3, Drawing sheet 1). On the other hand stretches of the flexures bring about discomfort and pain for the patient during the procedures. Passing more flexures during the procedure produce more friction and shearing forces, up to the point that colonoscope can no longer be pushed forward despite great pushing effort and pushing the tube will only result in producing a loop in more redundant portion of the colon such as sigmoid or transverse colon which brought-more pain and discomfort for the patient.
There are several colonoscopic maneuvers that have been proposed to overcome this problem. These maneuvers try to bring the colonoscope in to a straight position by hooking the tip of the colonoscope (FIG. 4, drawing sheet 1) and shortening (straightening) of the colonoscope (FIG. 5, drawing sheet 1). These maneuvers decrease the bends and flexures by aligning them in a nearly rectilinear position to reduce the friction and shearing forces (FIG. 6, drawing sheet 1) and this leads to better transmitting of the pushing force to the tip of the colonoscope.
The idea of creating this device dawned on me during a burdensome colonoscopic procedure. The colonoscope was stuck in the hepatic flexure of a 60-year-old man suspicious of having a cecal tumor who had a redundant, tortuous colon. Meanwhile I was in absolute despair of accomplishing a pancolonoscopy, I tried to pull the mucosa toward the fiberoptic colonoscope by grasping the distant bowel mucosa by biopsy forceps. After several attempts (and several untoward mucosal biopsy takings), the colonoscope moved just a bit forward and this enabled me to hook the tip of the colonoscope over the flexure and short the colonoscope to bring it in to a straight position. Eventually a successful pancolonoscopy was performed in that case. Although using biopsy forceps for pulling the colonoscope onward might be useful in some circumstances, but the grasped mucosa usually returns to its previous position as soon as it become released. The other problem is the obscuring of the luminal view by the mucosa approaching the colonoscope.
Initially I proposed a simple method for pulling the colonoscope forward. In this method I used two plastic flexible tubes which were secured along the side of the conventional colonoscope by its full length by an ordinary bonding strip. These tubes make it possible to transfer two biopsy forceps simultaneously to the tip of the colonoscope and grasp the mucosa successively to prevent reverting of the mucosa after releasing. The major problem of this simple device was multiple untoward mucosal biopsy takings, making several mucosal artifacts that might be mistaken for mucosal lesion.
Creeping colonoscope applies the same mechanism for moving ahead but lacks those disadvantages by replacing sucking arms instead of biopsy forceps. This resembles climbing a ladder, where hands could assist the climbing force of the feet. The sucking arms adhere to the mucosa by sucking pads and would pull the mucosa toward the tip of the fiberoptic colonoscope. Successive repetition of this operation not only pulls the mucosa over the colonoscope but also moves the colonoscope tip toward the front. This provides a great improve t of the movement of the conventional colonoscope in the colon.
The mechanism for movement of the new colonoscope that I have designed has some similarities to the endoscopic robot by Dario P et. al. In patent U.S. Pat. No. 5,906,591 on May 1999. The endoscopic robot designed for being inserted in to a body cavity of a patient and advanced therein in a prefixed direction with a so called inch-worm like motion, comprising a variable length segment and aspiration means for selectively producing a pneumatic vacuum between robot and the body cavity wall, allowing the inch-worm like motion avoiding, at the same time any pushing action against the body cavity. But there are several major differences in the design of the endoscopic robot and creeping colonoscope:
1. Endoscopic robot is a robot that can be controlled from out side of the body and it is equipped with servomotor microarms, microcameras and laser emitter for diagnostic and possible therapeutic maneuvers. But creeping colonoscope composed of a conventional colonoscope (fiberscope) with a new improved mechanism of movement
2. The major force of the movement of the endoscopic robot is provided by its inch-worm movement independent of any external pushing force, while the creeping colonoscope is mainly dependant on external pushing force for its movement. Actually the pulling force is designed to be used only when the colonoscope is passing the flexures or stucked in the colon because of looping of the colonoscope in redundant portion of the sigmoid and transverse colon. PA1 3. The mechanism of action of the endoscopic robot is inchworm-like motion. It means that it has a proximal and distal part that can selectively adhere to the bowel mucosa by applying the vacuum. The intermediate portion is flexible and results in movement of the instrument during successive appliance of the proximal and distal vacuum adherence. The mechanism of the action of the creeping colonoscope composed of protruding and retracting of a pair of effectors that are mounted on the side wall of colonoscope tip. Each effector composed of an arm that is able to protrude forward in to the lumen after the release by a spring force, adhering to the mucosa via their sucking pad by vacuum power which would be applied after the protrusion, result in withdrawal of the sucking arm in to its initial position. Pulling forces would be generated by withdrawal of the protruded arm that will be adhered to the bowel mucosa and successive alternative appliance of a pair of these arms to the adjacent mucosa would be able to propel the colonoscope a few centimeters forward enough to pass the flexures. Although both instrument move by successive appliance of the vacuum to the mucosa, there are a great differences in the mode of vacuum appliance (fixed proximal and distal portion with flexible middle part versus retracting side arm appliance) and mode of movement (inch-worm movement versus ladder climbing using alternate hands) in these two instrument and the only similarity is the using pneumatic vacuum for movement. PA1 1. This device moves forward by pushing force of the expanded projections, while creeping colonoscope move forward by pulling force of the sucking arms. PA1 2. The colonic mucosa is elastic and easily could be pulled or pushed (high compliance). This characteristic of the colon will produce a great difficulty for the designed device to move in the colon. Therefore when the projections push the colonic wall backward to move the endoscope forward, they only move the colonic wall backward and after retraction of the projections the colonic wall return to its place. If the colonic wall were more rigid this instrument would move the endoscope forward. The creeping colonoscope use the sucking arm which adhere to the mucosa and pull it and keep it in this position till the second arm applied to the mucosa and pull the mucosa again. This action would be repeated successively by the pair of the arms. Repetition of this action will stretch the mucosa to the point that moving of the colonoscope forward is easier than moving the mucosa backward. In this situation the elastic force of the colonic wall would be reached or exceed the force that is needed to move the tip of the colonoscope onward. PA1 3. Adhering of the tip of the colonoscope to the mucosa by sucking arms secures the position of the colonoscope in the colon and enable the endoscopist to perform the hooking and shortening (straightening) maneuvers easily. This possibility is not provided by the proposed design.
The other device that has been designed for advancing an endoscope through a body passage was invented by Meiri, Through patent number U.S. Pat. No. 4,207,872, on June 1980. This instrument composed of a sleeve having an annular chamber defined in part by an outer wall of elastometeric material. A multiplicity of resilient hollow protrusions are formed in the wall and expand outwardly and rearwardly when the chamber is filled with a suitable fluid under pressure and which retract inwardly and forwardly when the pressure of the fluid is reduced. This device is secured to the distal end of endoscope and by repetitious expansion and retraction of the protrusion, such device would move forward. There are several differences between this invention and creeping colonoscope:
LeVeen invented another design of the similar instrument, which uses pneumatic bellows for generating pushing force to move a catheter inside a hollow cavity, through patent number of U.S. Pat. No. 4,389,208, on June 1983. This catheter advancer has similar mechanism of movement as was described for previous invention designed by Meiri, but the differences are presence of bellows rather than expanding projections and the propelled device is a catheter rather than an endoscope.
The other device in this field designed by Choy, with patent number of U.S. Pat. No. 3,895,637, on July 1975. This invention which has a complex design composed of multiple balloons and membranes for securing the endoscope in the lumen of the intestine and propel the device by inflating of the other balloons. This self propelled conduit-traversing device also use pushing force of the inflated balloons.
The other device that has been invented to move the long instrument inside the intestinal lumen was proposed by Krasner through patent number U.S. Pat. No. 4,676,228, on June 1987. This medical apparatus having inflatable cuffs and a middle expandable section and the mechanism of the movement is using multiple balloons (cuffs) and a portion that could be extended after securing of the balloons in the lumen.
There is another instrument that proposed to perform endoscopic procedure by robot. Robotic endoscopy was invented by Grudfest with the patent number U.S. Pat. No. 5,337,732, on August 1994. These device moves in the body cavity by a mechanism resemble inchworm or snake. A balloon fixes the robot tail inside the lumen after inflation. The extendable head then can move forward and then could be secured inside the lumen by another balloon till the tail retract the reach the head. This repetition of the inflating and deflating balloons and moving multiple segments moves the robot inside of the body cavity. This robot is also provided with microcamera and multiple arms to perform diagnostic or therapeutic procedures.
Other apparatus that is invented for endoscopic examination designed to move an endoscope by transmitting burst of energy wave (radiofrequency or ultrasonic) to the end of the endoscope and provide inflation of the balloons for movement of the endoscope. Frazer through U.S. Pat. No. 4,176,662 invented this device, on December 1979.
Other lumen-traversing ice was invented by Oritz with patent number U.S. Pat. No. 5,398,670, on March 1995. This instrument also uses three balloons and a moveable middle portion. Another insertion assisting device for medical instrument was designed by Kruger, through patent number U.S. Pat. No. 5,454,364, on October 1995. This instrument uses inflatable chamber, which push the intestinal wall to move the endoscope with the inertia force of the pushed wall.